Heavy hydrocarbons such as bitumen, kerogen, GILSONITE (a registered trademark of American Gilsonite Company for a mineral known as asphaltum, uintaite or uintahite), and tars are high molecular weight hydrocarbons frequently encountered in subterranean formations. These hydrocarbons range from thick viscous liquids to solids at ambient temperatures and are generally quite expensive to recover in useful form. Bitumen occurs naturally in tar sands in locations such as Alberta, Canada and in the Orinoco oil belt north of the Orinoco river in Venezuela. Kerogens are the precursors to fossil fuels, and are also the material that forms oil shales. Kerogens, believed to be the precursor to bitumens, are frequently found in sedimentary rock formations.
Heavy hydrocarbons in general, have been used in a number of applications such as in asphalt and tar compositions for paving roads and roofing applications and as an ingredient in waterproofing formulations. Importantly, they are a potentially valuable feedstock for generating lighter hydrocarbons. This is typically accomplished by thermal cracking and hydrogenolysis processes, for example.
Recovering heavy hydrocarbons whole or as lighter hydrocarbons and/or natural gas by thermal cracking in subterranean formations continues to be a challenge. The excessive temperatures necessary for thermal (or steam) cracking (about 850° C.) requires expensive, complex technology due to the special construction material to sustain high cracking temperatures and high energy input. Hydrogenolysis has limited utility when the recovery of lighter hydrocarbons is desirable. This is due to the difficulty of separating hydrogen from light olefins such as ethylene, propylene, and natural gas. Therefore, there is a continuing need for the development of methods for producing light hydrocarbons and natural gas from high molecular weight hydrocarbon feedstocks.